A number of applications exist for apparatus and systems for thoroughly mixing or blending two or more fluids together, forming a resultant mixture having unique properties attributable to the mixture. For many applications, the mixing of the fluids presents no particular problems, particularly where the two fluids are liquids of low viscosity. For such liquids the particular manner in which they are mixed is not of much significance, and aspirating systems or systems which merely pour the liquids together in a container with little or no agitation will result in the desired blending.
For liquids of substantially different viscosities, however, or where both liquids are highly viscous, considerable difficulty is encountered in achieving a complete blending or mixing of two different liquids together. Of course, pouring the liquids together in a tank with agitating blades or the like churning through the liquids results, after some length of time, in a thorough blending of such liquids. Many applications, however, do not readily adapt to this type of mixing; and it is desirable to supply the two diffferent liquids in continuously moving high velocity streams to a mixing chamber to produce the resultant blended liquid at the output of the mixing chamber or mixing point. One such application is in the area of fire-fighting where it is desired to introduce a polymer thickener into a flowing water stream to produce a resultant thickened mixture for application to the fire. The mixing for this application must be continuous and at relatively high rates of flow and volume of the liquids used.
In the past, the mixing of a polymer thickener with a high velocity water stream has been achieved by utilizing special nozzles and special constructions of mixing chambers in order to create the desired turbulence in the liquid flow to produce sufficient hydraulic shear in the polymer liquid solution to effect the thorough blending of the polymer solution with the water carrier stream. The use of such nozzles results in head or pressure losses in the fluid stream; and in many cases this is highly undesirable. In addition, the utilization of complex mixing chamber configurations or special nozzles results in additional manufacturing costs and resultant maintenance problems in the mixing equipment.
Another solution in the past has been to introduce the polymer thickener into the water carrier stream in front of a pump, which then draws the thickener and water together through the pump impeller. The impeller blades then serve the dual purpose of pumping and slicing the polymer into the water to minutely subdivide the thickener and uniformly disperse it in the pump discharge. To pass the thickened mixture through the pump creates potential maintenance problems which would not occur if this were not done.
It is desirable to achieve thorough blending of a polymer thickener with a carrier solution such as water in a simple, efficient and inexpensive device.